The Trend CB counterbore is extensively used for recessing bolt and screw heads Supplied with a HSS slow spiral drill bit Fully adjustable a hex key is supplied TCT version is used for plywood particle boards and plastics abrasive To be used at drilling speeds only they are not suitable for ferrous and non-ferrous metals When setting up ensure flutes of drill are aligned with flute of counterbore For replacement Twist Drills use slow spiral type eg 501532 to 501012 D 95mm D2 396mm OL 75mm